Stitching unitizer

ABSTRACT

A sewing machine which has the capability to continuously stitch a traveling relatively hard material with a tight chain stitch utilizes a reciprocating sewing head, and a reciprocating thread thrower, together with appropriate stitching conveyors. Continuously moving material is fed into a sewing station by upper and lower stitching conveyors such that as the material passes through the stitching station, it is generally in a horizontal flat plane. At the stitching station, individual holes are continuously punched and a vertically and axially reciprocating needle then enters the hole and has a thread loop positioned thereon. As the needle travels downwardly while at the same time moving axially carrying the thread loop with it, it will travel through a previously picked off thread loop which is waiting on a looper mechanism. The stitching cycle is continuously repeated and this action establishes a straight stitched thread line comprised of individual chain stitches.

United States Patent Brookhyser et al.

3,732,833 May 15, 1973 STITCHING UNITIZER Primary Examiner-James R. Boler [75] inventors: Byron Brookhyser, Milton; Attorney-Patnck D. Coogan, John M. Crawford, Harold E. Erickson, Federal Way, Stuart Heller and Bryan both of Wash. Ogden [73] Assignee: Weyerhaeuser Company, Tacoma, [57] ABSTRACT wash' A sewing machine which has the capability to continu- [22] Filed: June 7, 1971 ously stitch a traveling relatively hard material with a tight chain stitch utilizes a reciprocating sewing head, [21] Appl' 150494 and a reciprocating thread thrower, together with appropriate stitching conveyors. Continuously moving 52 us. c1 ..112 203, 112 21 material is fed into a sewing Station y PP and 51 Int. Cl. ..B42b 1/02 lower Stitching conveyors Such that as the material 58 Field of Search ..112/121.14, 21, 203, Passes thmugh stimhing Station, it is generally in a 112/206 213 214 161/101 horizontal flat plane. At the stitching station, individual holes are continuously punched and a vertically and axially reciprocating needle then enters the [56] References Cited hole and has a thread loop positioned thereon. As the UNITED STATES PATENTS needle travels downwardly while at the same time moving axially carrying the thread loop with it, it will Cl 8,. X travel through a previously off thread loop 2,217,967 10/1940 Phlll lps -112/203 X which is waiting on a looper mechanism. The stitching 2,009,172 7/1935 Fraz1er ..112/21 cycle is continuously repeated and this action 3,024,746 3/1962 Hlldmann 112/21 establishes a straight stitched thread line comprised of FOREIGN PATENTS OR APPLICATIONS md'vdual smches' 787,151 12/1957 Great Britain ..112/206 5 Claims, 14 Drawing Figures 57 o as o if} 55 o 54 PATENTED 3,732,833

SHEET 1 OF 6 AT OP/VE V6 BACKGROUND OF THE INVENTION The present invention relates generally to an apparatus for stitching relatively solid material as it passes through the stitching station. More particularly it relates to a sewing machine of the type for making chain stitches for joining together individual pieces of wood veneers.

While the instant invention was conceived in order to unitize core wood veneers it should be appreciated that the apparatus has utility with different types of material. The core wood veneer is usually of random width resulting from the clipping out,of the more serious defects, many pieces of core veneer being quite narrow to avoid waste of any usable wood. In many plywood manufacturing plants it is common practice to utilize this narrow core veneer individually to make the plywood panels. That is, each narrow strip of core veneer is passed through a glue spreader and is then selectively positioned in the forming plywood panel.

Since the interior core veneers, whatever their width, are very thin ranging from about 1/32 inch to 1 inch it should be appreciated that it is desirable to provide some means for forming these narrow strips of core veneer into an integral sheet which can then be utilized in the panel layup process as a single sheet. This of course tends to reduce the time necessary for forming the full plywood panel. Unitized core as it is known to those skilled in the art also is much easier to handle either with respect to transporting a stack of unitized core or with respect to handling individual units as when laying up the plywood panels.

Thus it has been the practice in many plywood manu facturing plants to provide means for establishing a unitized sheet of core veneer which comprises a number of separate pieces of veneer disposed in a joined together edge-to-edge relationship so that there will be no spaces or gaps in the interior of the panel. Several means are known to the prior art for unitizing core veneers. One such method included adhesively bonding the adjacent edges of the individual core veneer strips together. It will of course be realized that the strength of a joint formed by end gluing will be rather low in addition to the fact that the production rate when utilizing this method is extremely low for commercial production. Another method utilized in the prior art was that of stapling the adjacent edges of the individual core veneer strips together. It has been found that by utilizing staples there is not a sufi'icient retention characteristic to hold the pieces together in a unit satisfactory for plywood layup. Yet another method known to the prior art was that of placing adhesive coated tape or adhesive coated string across the faces of the abutting core veneer strips whereby they would then form an integral core veneer sheet. This method also lacked sufficient retention characteristics as well as being objectionable because it was uneconomical due to the expense.

One example of a particular method for unitizing core veneer strips is that disclosed in the issued US. Pat. No. 3,135,644. This patent entitled Continuous Veneer Core and Method and Apparatus for Making the Same" was issued in the names of Lewis H. Coplen et al. and as been assigned to the assignee of the present invention. This particular method utilizes an edge taping apparatus whereby individual core veneer strips are abutted end to end and a piece of suitable tape is positioned along the edges normal to the abutting edges. it was an object of this method to temporarily unitize the core in order to allow more efiicient layup and then trim oi? the edges where the tape had been placed consequently wasting a substantial amount of wood veneer.

It had been suggested that a suitable method of joining core veneer strips together would be an appropriately designed sewing machine whereby the abutting edges of the veneer strips would actually be sewn together with a suitable stitch. There are many sewing machines known in the prior art that may be utilized to work with relatively hard material such as wood veneers.

One example of a prior art sewing machine is that shown in the issued US. Pat. No. 3,024,746 to W. B. Hildmann entitled Book Sewing Machine. The principal object of this particular invention was the provision of a machine for side stitching heavy books with a full lock stich at relatively high production rates. It utilizes an individual drill for positioning the aperture within the work piece. The one disadvantage to this particular sewing machine is its intermittent operation, that is the work piece was intermittently fed through the sewing station whereby resulting in relatively low production when thinking in terms of veneer core unitizing. Another example of a prior art sewing machine is one which is manufactured by the Puritan Manufacturing Company, a division of the Torrington Company, Torrington, Connecticut. The Puritan sewing machine is a high-speed device which operates on leather goods for making luggage or the like. The particular sewing machine produces a uniform chain stitch at a rate from 1500 to 2000 stitches per minute, but again it operates in an intermittent motion as the work mate rial passes through the sewing station. Another problem which was discovered when attempting to apply the Puritan sewing machine to core veneer was that of inadequate void stitching. That is, as a void in the veneer passed through the sewing station the string would break and tended to cause problems when the machine continued to stitch in the solid material.

The difficult problem with the intermittent motion of the core veneer through the sewing machine is that it is extremely susceptible to breakage and any sudden repeated start-stop action will tend to break it apart. Of course with solid leather material or book material this does not represent the problem as it does with large sheets of relatively brittle, fragile core veneer.

The basic assumption when considering unitizing core by a stitching means is that a thread material is in fact acceptable in the glue line by way of industry and governmental standards. It has been found that a plywood panel having stitched unitized core is in fact acceptable and is just as strong as, if not stronger, than plywood panels having core unitized according to the prior art.

When designing a core unitizing sewing machine, other factors must be considered in addition to the ones noted above. A primary requirement of the unitizing sewing machine is that it be operable to accept crowded core from the crowder section and maintain it in the crowded configuration while the stitching operation is carried out. This function is extremely impor tant because a strong joint between sections of core is required. At the joinder point between adjacent core veneers, the sewing machine must provide a good tight stitch which depends both on the characteristics of the sewing machine as well as the type of thread used. In the present invention, all mechanical elements functioning together and in harmony will provide the tight stitch while a strong rayon thread will provide strength in the joint. Of course, it is understood that while a rayon thread is desirable, it is not the only type of thread that is suitable for the present invention; other suitable threads may be used.

Another factor to consider in designing the sewing machine is that its physical size must be such that a plurality of the sewing machines can be positioned laterally across a conveyor surface as the strips of core veneer travel into the plurality of sewing machines. This, of course, is necessary since the normal size for core veneer is on the order of 4 feet by 8 feet and it will be appreciated that at least two stitched lines of thread will be necessary to properly unitize the core. It will also be appreciated that other arrangements may be designed which will be obvious to those skilled in the art, such as unitizing 8-foot strips of core veneer and then cutting the unitized core in half to form the 4 X 8 core panels. In this manner at least four sewing machines are required and must be laterally displaced across the width of the stitching conveyor.

As had been pointed out previously, a continuous motion is desirable as the core passes through the sewing machine. It, of course, is understood that the faster the stitching can be done, the more production will be realizable. When machines are designed with many moving parts with rather complicated motions, there is a limiting feature in the number of stitches that can be made for a unit of time. It is, however, desirable to convey the core veneer strips through the sewing station as fast as possible within mechanical limits. It has been found that by utilizing the present design, core veneer may be fed through the sewing station at a rate on the order of 75 linear feet per minute. At this linear rate, the sewing machine will be stitching approximately 2,000 stitches per minute. It should be appreciated that with a relatively large sewing machine with a large mass this is an excellent production rate.

With the rapid speeds of stitching that are required, frictional heat often becomes a problem. For this reason, the device that punches the hole in the core veneer is, in fact, separate from the needle in order to reduce the buildup of frictional heat. Utilizing this method, the separate punch places a continuous line of holes in the core veneer and subsequently the needle is caused to travel through each hole and, with all parts properly timed, the needle will not contact any portion of the core veneer. Thus the frictional heat built up around the needle is greatly reduced.

Accordingly, from the foregoing, one object of the present invention is to provide a sewing apparatus for stitching relatively hard material.

Another object is to provide a sewing machine which will stitch the relatively hard material as it continuously passes through the sewing station without intermittently starting and stopping.

Another object is to provide a sewing machine which will yield a strong tight chain stitch in order to join together strips of core veneers.

Still another object is to provide a sewing machine which will continue to hold the crowded core veneers together as they pass through the sewing station in order to produce the tight joints.

Yet another object is to provide a sewing machine and stitching cycle that will produce good tight stitches over voids in any material that passes through the sewing station.

The primary object of the instant invention is to provide a machine which will efiiciently unitize strips of core veneer at a fast production rate.

These and other objects of the invention will become apparent upon reading the following specification in conjunction with the attached drawing.

SUMMARY OF THE INVENTION Briefly stated, this invention is practiced in one form by positioning a reciprocating sewing head beneath a sewing station and which is adapted to reciprocate in the axial direction. Positioned vertically above the sewing station and in operative communication with the sewing head is the axial and laterally reciprocating thread thrower assembly. The bottom sewing head has a needle and looper assembly which reciprocates both axially and vertically and which operates in close communication with the upper thread thrower in order to form the tight chain stitch. An individually operating punch assembly reciprocates in a manner similar to the needle but is positioned axially upstream from the needle. and looper assembly in order to punch holes within the traveling core veneer. A plurality of stitching conveyors are in operative communication with the moving parts of the sewing station in order to feed the crowded core veneer through the sewing station with the proper timing in relation to the sewing action.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view partly in section and shows the general arrangement of parts at the sewing station.

FIG. 2 is also a side elevation view and depicts the relationship of the several driving chains and stitcher conveyors with respect to the sewing station.

FIG. 3 is a side elevation view partly in section similar to FIG. 1 but shows the interlocking gears for the axial and vertical reciprocation movement.

FIG. 4 is a front elevation view in section taken along lines IV-IV of FIG. 3.

FIG. 5 is a complimentary view to FIG. 3 and depicts the action of the axial movement exerted on the sewing head by the operation of the oscillator mechanism.

FIG. 6 is a front elevation view partly in section taken through lines VIVI on FIG. 1.

FIG. 7 is a side elevation view partly in section taken through lines VII-VII of FIG. 6 and depicts the cam, push rod, and lever arm assembly for the looper wishbone.

FIG. 8 is a similar side elevation view partly in section taken along lines VIIIVIII of FIG. 6 and depicts the connecting rod and piston assemblies for the punch and needle.

FIG. 9 is also a side elevation view partly in section taken through lines IX-IX of FIG. 6 and depicts the cam, push rod, and lever arm assembly for the looper yoke.

FIG. 10 is an isometric view partly cut away and in section showing the looper mechanism at the upper portion of the sewing head.

FIG. 11 is a similar isometric showing the thread thrower assembly in relation to the traveling core veneer.

FIGS. 12, 13, and 14 depict the sequence of the chain stitch formation by way of needle, thrower, and looper action.

DESCRIPTION OF THE PREFERRED EMBODIMENT Prior to fully describing the core veneer sewing machine, a directional convention will be established. Referring to FIG. 1, the longitudinal or axial direction will be taken as the direction of veneer travel through the stitching station which in FIG. 1 is a horizontal plane in the direction of the travel arrow. The vertical direction will be a plane up and down through the stitching station while the lateral direction is the plane which is through the stitching station into the drawing. When various motions or elements are referred to with a directional description, this convention will be the standard.

Referring now to FIG. 1, a general structural layout of the sewing machine will be described. The stitching station is generally indicated as 1 and is comprised basically of a reciprocating sewing head 2 and a reciprocating thread thrower 3. The reciprocating sewing head 2 is mounted in a stationary base or supporting member 4 while the reciprocating thread thrower 3 is mounted on a stationary member 5. The respective supporting members 4, 5 are in turn removably mounted on a pair of laterally extending stationary shafts depicted as 6 and 7. The sewing head mounting shaft 6 extends laterally a sufficient distance to accept the lateral dimension of the base member 4 and has a laterally extending key member 8 and thread holding means 9 for securing the base member 4 to the mounting shaft 6. It should be appreciated that if a plurality of sewingmachines constructed according to the present invention are to be utilized in stitching a plurality of thread lines, the laterally extending mounting shaft 6 will extend the total lateral dimension across which the core veneer sheets extend. The reciprocating sewing heads 2 and their respective base members 4 will then be laterally positioned across the mounting shaft 6 and keyed into final position. It will be further understood that the laterally extending mounting shaft 6 is in turn positioned in a fixed manner to any suitable lower frame means, depicted generally in FIG. 2 as element 10.

In a like manner, the upper laterally extending mounting shaft 7 accepts the stationary supporting member 5 at the proper lateral position and a suitable holding device 11 fixes the support member 5 on the mounting shaft 7.

An upper stitching conveyor 12 and lower stitching conveyor 13 operate in the axial direction according to the directional arrow to move the strips of core veneer which are in a crowded condition through the stitching station 1. The axially extending stitching conveyors I2, 13 form between their adjacent faces an axially extending stitchingplane generally indicated as 14 through which the strips of core veneer pass. It is the function of the stitching conveyors l2, 13 to hold the traveling veneer strips in the horizontal stitching plane 14 in order to offer the proper relationship of the veneer strips to the stitching station 1. It should be appreciated that the stitching conveyors 12, 13 are generally endless chains 15 with a plurality of rubber members 16 attached thereto in order to provide a gripping action against the strips of core veneer.

It should be appreciated that since the endless chain 15 and rubber members 16 of the lower stitching conveyor 13 will be somewhat flexible in the vertical direction a suitable supporting element 17 should. be provided so as to maintain the stitching conveyor 13 at its proper vertical height particularly at the stitching station 1. The configuration of the supporting element 17 may be seen better by referring to FIG. 6 where it is depicted as being comprised simply of a recessed plate member 18. The recessed plate member 18 extends generally laterally and axially through the stitching station 1 and is slightly below the horizontal stitching plane 14. As seen in FIG. 6, the recesses being depicted as 19 and 20 respectively, support the endless chains 15 such that the rubber members 16 will be supporting the traveling core veneer through the stitching station 1.

As previously mentioned, the reciprocating sewing head 2 is mounted in the base member 4 in such a manner that it is allowed to pivot axially back and forth about a pivot point which is generally indicated in FIG. 1 as 21. The details of the pivot mounting means will be understood by referring to FIGS. 1, 3, 5 and 6, wherein the mounting means generally indicated as 22 in FIG. 1 are more clearly depicted. The reciprocating sewing head 2 which is an integral unit has a pair of laterally opposed mounting wheels 23 and 24 respectively. These are rotatably mounted at the bottom of the sewing head case generally indicated as 25 and are adapted to allow the sewing head 2 to reciprocate axially about the pivot point 21. The pivot point 21 is, in fact, the crankshaft for the vertically reciprocating parts of the sewing head 2 and will be fully described later. However, it should be appreciated that the mounting wheels 23, 24 could be rotatably mounted on the crankshaft as opposed to being rotatably mounted on the sewing head case 25. The pair of opposed side walls 26 and 27 which comprise the base member 4 extend generally downward from the supporting element 17 and terminate with a pair of vertically extending sides 28 and 29 as seen in FIG. 1. The vertically extending sides 28, 29 are recessed and have respective tracking means 30 and 31 for the acceptance therein of the grooved mounting wheels 23, 24. In order to fixably mount the mounting wheels 23, 24 so that the entire sewing head 2 is in its proper spatial relationship with respect to the stitching station 1, a pair of oppositely mounted pivotal holding plates 32 and 33 are adapted to accept the other side of the mounting wheels 23, 24 respectively. Utilizing the pivotal holding plates 32 and 33, it will be appreciated that the entire sewing head 2 may be easily removed by unlocking the simple tension holding devices depicted as element 34 in FIG. 1. Upon securing the sewing head 2 in its base member 4, the tension member handle 35 is then placed in the locked position. The hook of the tension holding means 34, of course, is in secured communication with the stationary base member 4 when the handle 35 is in the locked position. Similar devices are, of course, well known in the art and a further description is deemed unnecessary for the present invention.

By so mounting the sewing head 2, the upper portion is then free to reciprocate axially about a small arc of travel. The axial motion imparted to the sewing head 2 is provided by an oscillating mechanism generally indicated as 36 and briefly is comprised of a pair of axially reciprocating arms 37 and 38 which in operative motion impart a compound motion to the pivot point 39 of the joining arm member 40. A pivotally mounted connector member 41 then imparts the axial motion at the pivot point 39 to the sewing head 2. The details of the axially reciprocating motion imparted to the sewing head 2 will be more fully described later when referring specifically to FIGS. 3, 4, and 5.

Comprising an integral part of the reciprocating sewing head 2, but adapted to reciprocate vertically therein, are the hole punching mechanism 42 and the stitching needle mechanism 43. Also comprising a part of the sewing head 2 is the vertically, laterally, and axially reciprocating looper mechanism depicted generally as 44 in FIG. I. The hole punching mechanism 42 and stitching needle mechanism 43 are adapted to reciprocate vertically such that their extreme tip portions will reciprocate above and below the horizontal stitching plane 14. Positioned above the horizontal stitching plane 14, and in close proximity with the area of the needle travel, is the generally horizontal foot member 45. Foot 45 acts to stabilize the thread, needle, and core veneer during the throwing operation.

Another element that performs a stabilizing function is the rotatable punch wheel 46 which is mounted on the punch wheel frame 47. The punch wheel 46 is positioned directly above the axial position at which the hole punching mechanism 42 punches an individual hole in the traveling core veneer. Comprising the punch wheel 46 is a pair of spaced-apart wheels 48 and 49 having a chain drive sprocket (not shown) therebetween. This may be clearly seen by referring to FIG. 10. An endless chain 50 communicates with the sprocket which is positioned between the pair of wheels 48, 49. The depth of the periphery of the endless chain 50 is such that the hole punching mechanism 42 can extend upwardly through the veneer without contacting any part of the rotatable punch wheel 46. The primary function, of course, of the punch wheel 46 is to provide suitable holding pressure between the lower stitching conveyor 13 and the wheels 48, 49 which are in rotatable contact with the traveling core veneer. By so stabilizing the core veneer, the punching mechanism 42 will make a clean positive hole each time. A portion of the upper frame means is indicated as 51 in FIG. 2 and is comprised of the support means 52 for-the endless chain 50.

The endless chain 50 is trained about an upper sprocket wheel 53 and a lower sprocket wheel 54 respectively. The lower sprocket wheel 54 is pivotally mounted to the support means 52 and maintains tension on the endless chain 50 through a rearwardly extending spring 55. In the embodiment depicted in the figures, the upper sprocket wheel 53 is powered and as such, causes the punch wheel 46 to act as additional driving means for the traveling veneer. The power connection for the upper sprocket wheel 53 will be described when referring particularly to FIG. 2.

Another important element which is generally depicted in FIG. 1 is the threat tensioning apparatus indicated generally as 55. In the embodiment depicted, a spool of thread (not shown) is positioned vertically above the stationary supporting member and the single thread is trained through the tensioning apparatus 55 downwardly through the thread thrower 3. This apparatus will be more fully described when referring specifically to FIGS. 6 and 11.

Turning now to FIGv 2, the overall driving mechanism will be described as will the various driving and idler shafts. A single drive motor of any suitable type (not shown) operates to drive the main drive shaft 56. The drive motor is preferably of a type which is speed variable in order to provide different veneer feed rates and different stitching rates. The main drive shaft 56 is rotatably mounted within the lower frame means and is positioned vertically beneath the pivot point 21.

The main drive shaft 56 extends laterally beyond the side walls 26, 27 in order to accommodate a plurality of gears and sprockets to be subsequently described. Emanating from the drive shaft 56 are a plurality of endless driving chains. The stitching conveyor drive chain 57 is trained about asuitably positioned drive sprocket 58 which is securely fixed to the main drive shaft 56. The opposing end of the drive chain 57 is trained about a common drive socket 59 which, through a suitable reduction device 60, drives the upper and lower stitching conveyors l2 and 13. It will, of course, be appreciated that a plurality of gears are contained within the gear reduction device 60 in order to reduce the speed of the stitching conveyors l2 and 13, such that they both travel with the properly selected uniform axial motion along the horizontal stitching plane 14.

The upper and lower stitching conveyors l2 and 13 must be properly guided and a plurality of sprocket members and guiding frames are provided. At the downstream end of the core unitizing sewing machine, the stitcher conveyors are trained about upper and lower sprocketmembers indicated as 61 and 62 respectively. The upper and lower sprocket members 61, 62 are positioned vertically apart but generally on the same vertical plane such that when their respective stitching conveyors 12 or 13 are trained about the sprocket members, the opposing rubber members 16 of each stitching conveyor will form the horizontal stitching plane 14. Both the upper and lower stitching conveyors 12, 13 then proceed axially upstream within suitable upper and lower guide means 63 and 64 respectively. At the upstream end of the horizontal stitching plane 14, the upper and lower stitching conveyors l2 and 13 are respectively trained about upper and lower upstream reversing sprockets 65 and 66. These two sprockets 65, 66 are idler sprockets and merely serve to reverse the direction of the stitching conveyor direction.

It will be appreciated that in order to properly support the traveling core veneer through the stitching station 1, it will be necessary to have at least two laterally spaced upper stitching conveyors l2 and at least two laterally spaced lower stitching conveyors 13. In a core unitizing sewing machine where a plurality of reciprocating sewing heads 2 and thread throwers 3 are spaced laterally in order to sew a wide piece of core veneer, it will be understood that additional upper and lower stitching conveyors will be utilized, the only requirement being that they are properly spaced such that they do not interfere with the other moving elements.

One function of the cooperating upper and lower stitching conveyors 12, 13 is to securely grip the crowded core veneers and hold them in such a configuration as the crowded veneer travels axially downstream and as it enters the stitching station 1. A suitable crowding device, several of which are known to the art, is positioned axially upstream from the input end of the upper and lower stitching conveyors 12, 13. An example of a suitable crowding device may be seen by referring to the issued US. Pat. No. 3,135,644 granted to L. H. Coplen et al. and assigned to the assignee of the present invention. A crowding device, as will be understood by those skilled in the art, is merely, in broad terms, a pair of conveyor surfaces traveling at different speeds in order to crowd the strips of core veneer together in an edge-to-edge abutment relationship.

Of course, it will be appreciated that the upper and lower stitching conveyors 12, 13 will require other supporting means in order to prevent unwanted vibration and to keep them tight and in smooth running condition. The upper stitching conveyor 12 has, for example, a pair of idler sprockets depicted as 67 and 68 respectively which are positioned axially apart and vertically above the upper sprocket member 61 and upper reversing sprocket 65. The idler sprocket 67, 68 are mounted on suitable laterally extending shafts 69 and 70 respectively which are in turn rotatably mounted within a portion of the upper frame means 51. Between the idler sprocket 67 and the upstream upper reversing sprocket 65 the upper stitching conveyor 12 is vertically supported by a suitable laterally extending support plate 71 which in turn is mounted at the proper vertical height on an upwardly extending portion 72 of the bottom frame means 10.

A shorter upper stitching conveyor 73 is similar in all respects to the longer upper stitching conveyor 12, ex cept that instead of being trained about the upper reversing sprocket 65, it is trained about a suitably mounted reversing sprocket 74 which is positioned horizontally downstream from the sprocket 65. In a similar fashion, the rubber members 16 of the shorter stitching conveyor 73 form the horizontal stitching plane 14 with the rubber members 16 of the bottom stitching conveyor 13.

The lower stitching conveyor 13 is, as previously mentioned, supported vertically through the stitching station 1 by the recessed plate member 18 (see FIG. 6). Continuing axially upstream from the stitching station 1, the bottom portion of the lower stitching conveyor 13 is supported by an upstanding idler sprocket member 75 which is attached to a portion of the bottom frame means 10. An additional idler sprocket 76 is mounted just upstream from the upstanding idler sprocket 75 and is adapted to provide both a training function for the longer lower stitching conveyor 13 and as a reversing sprocket for the additional lower shorter stitching conveyor 77 which is similar to the shorter upper stitching conveyor 73.

It will be understood by those skilled in the art that a plurality of laterally extending horizontal support members collectively depicted as 76 will act in cooperation with the upstanding members of the bottom and upper frame means 10, 51 in order to provide structural rigidity for the stitching conveyors and the stitching station I. The primary requirement for these supporting members is that they do not interfere with any of the moving elements.

ln addition to the stitching conveyor drive chain 57 which is driven by the main drive shaft 56, a triangularly trained drive chain 79 is driven by the motor powering the drive shaft 56. At one apex of the drive chain 79, a driving sprocket 80 is mounted so as to drive a reduction device 81 which is mounted on a portion of the frame means and is operable to drive a pair of axially extending line shafts 82 and 83 respectively. The pair of line shafts 82, 83 may be operable to power any upstream or downstream function as the core unitizer installation might require. As an example, the line shaft 83 could provide the power to drive an off-feed stacker which would operate to stack sheets of unitized core veneer. Likewise, as an example, the line shaft 82 could provide the power to operate the upstream crowder.

At the remaining upper apex of the triangularly trained drive chain 79, a drive sprocket 84 is fixedly attached to the oscillator drive shaft 85 which in turn extends laterally through and is rotatably mounted within the vertical side walls 26,27. This may be seen clearly by referring to FIG. 6. The drive sprocket 84 is fixed to the drive shaft 85 at some position laterally spaced from both of the side walls 26, 27 such that the drive chain 79 will be allowed to drive the shaft 85 without interfering with the movements of the sewing head case 25. It will, of course, be appreciated that the oscillator drive shaft 85 is operable to carry out the function of the oscillating mechanism generally indicated at 36 in FIG. 1. Driven from a separately mounted sprocket (not shown) securely attached to the drive shaft 85 is the thread thrower chain drive 86. it will be appreciated, therefore, that the thread thrower chain drive 86 causes the thread thrower drive shaft 87 to turn at the same speed as the oscillator drive shaft 85. The thread thrower chain drive 86 extends upwardly from the drive shaft 85 to a position at the end of the thread thrower drive shaft 87 which is above the horizontal stitching plane 14. The thread thrower drive shaft 87 is rotatably mounted laterally through the stationary supporting member 5 and in turn is given additional vertical support by its appropriate mountings within the upper frame means 51. The mounting of the drive shaft 87 within the stationary supporting member '5 is clearly depicted in FIG. 11.

An additional driving mechanism to be noted is that which is driven from the idler sprocket 67. An additional driving sprocket is positioned laterally at the appropriate distance in order to communicate with the upper sprocket wheel 53 of the rotatable punch wheel assembly. The lateral positioning of the drive sprocket on shaft 69 will be generally in the same vertical plane as that of the sprocket wheel 53, Trained about the drive sprocket (not shown on FIG. 2) is a suitable drive chain 88 which is then trained about a suitably mounted driving sprocket 88a which is fixedly attached to the rotatable punch wheel drive shaft 89. Of course, it will be apparent to one skilled in the art that when the idler sprocket 67 is rotating so, too, will the drive chain- 88 which in turn will drive the endless chain 50 which operates the rotatable punch wheel 46. The punch wheel drive shaft 89 is rotatably mounted within the upper frame means 51.

Throughout the description of the present invention, reference is being made to a single laterally positioned sewing station A, but it should be appreciated by those skilled in the art as previously mentioned that a plurality of such sewing stations can be established across a lateral space depending upon the number of thread lines to; be stitched into the traveling core veneer. All of the aforementioned drive shafts and other elements can be laterally extended in order to drive the plurality of various moving elements with their additional sprockets and drive chains.

Turning now to a description of FIGS. 3, 4, and 5, a general description of the reciprocating movements will be described; that is, the reciprocating movement of the reciprocating sewing head 2. In FIG. 3, at the bottom portion thereof, the gear arrangement for taking power from the main drive shaft 56 and motivating the sewinghead 2 therewith is depicted. Mounted on the drive shaft 56 at a lateral position which is slightly displaced from one of the mounting wheels 23 or 24 is a fixed spur gear 90 (see FIG. 6). Spur gear 90 operates as the driving gear for the main crankshaft 91 which is within the sewing head case 25. As previously mentioned, the main crankshaft 91 also is effective as the pivot point 21. In drivable communication with the spur gear 90 is the crankshaft spur gear 92 which has the same number of teeth as does gear 90. Thus, by driving the spur gear 92, the main crankshaft 91 is rotated to provide the vertical reciprocation for the sewing head elements (stitching needle mechanism 43, looper mechanism 44, and hole punching mechanism 42).

The general details of the axial oscillating mechanism 36 will'be described in relation to providing the axial reciprocating movement to the sewing head 2. As previously mentioned, the oscillating mechanism 36 imparts a finely structured axial reciprocating motion to the moving elements of the sewing head 2; that is, to the hole punching mechanism 42, stitching needle mechanism 43, and looper mechanism 44. The structure of the oscillating mechanism 36, in addition to the previously mentioned axially reciprocating connecting arms 37, 38, connecting compound arm member 40 and connector arm 41, is comprised of the oscillator drive shaft 85 and a cooperating second drive shaft 93. As previously noted, the oscillator drive shaft 85 extends through and is rotatable within the side walls 26, 27 of the stationary base member 4. In a like manner, the second cooperating drive shaft 93 is positioned within the base member4 at a position directly above the drive shaft 85. and is rotatable about a lateral axis which is in a common vertical plane with the lateral axis of the drive shaft 85. Mounted on the cooperating drive shafts 85 and 93 are upper and lower cooperating spur gears depicted as 94 and 95 respectively. The lower spur gear 95 is structured in order to have twice as many cooperating teeth as does spur gear 94. Thus, it will be apparent that the second drive shaft 93 turns at one half the speed of the drive shaft 85. The respective spur gears 94, 95 are, of course, fixedly mounted by key means in the proper lateral position on their respective drive shafts.

Positioned on the respective drive shafts 85, 93 are a pair of eccentrics 96, 97 which, as will be appreciated by those skilled in the art, will impart the axial reciprocating motion to the reciprocating connecting arms 37, 38. This structure may be seen by referring to FIG. 4. The details of the dimensioning 'for the pair of eccentrics 96, 97 will be clarified under the description of the operation but it will be mentioned here that the ratio of the throw produced by the eccentrics is approximately 1:4 from the upper eccentric 96 to the lower eccentric 97. The connecting arms 37, 38 are then connected to the eccentrics 96, 97 in the correct relationship through journal means or the like. By referring to FIG. 5, an example of the resulting axial motion imparted to the sewing head 2 may be seen. Both of the connecting arms 37, 38 reciprocate axially back and forth and since both are pivotally connected on their respective downstream end to the connecting arm compound member 40, the compound axial motions will be summed at the pivot point 39 and imparted to the connector arm 41 which, as previously mentioned, is securely fixed to the sewing head case 25. The intent of the reciprocating axial motion is to allow the hole punching mechanism 42 and stitching needle mechanism 43 to move axially with the traveling core veneer after they have penetrated the veneer. This will allow continuous travel of the core veneer through the stitching station 1 without interference between the veneer and needle and punch and will greatly increase production of unitized core veneer.

Referring back to FIG. 4, a plurality of spacing members which may be bearings and/or spacers indicated collectively as 98 are laterally positioned along the respective drive shafts and 93 in order to maintain the primary positions for the pair of eccentrics 96, 97 and pair of spur gears 94, 95.

Turning now to a detailed description of the reciprocating sewing head 2 and the hole punching mechanism 42, stitching needle mechanism 43, and looper mechanism 44, reference will be made to FIGS. 6 through 10. As previously mentioned, the main crankshaft 91, which is rotatably mounted within the sewing head case 25, operates as both a crankshaft and a camshaft in order to reciprocate vertically the hole punching mechanism 42 and the stitching needle mechanism 43 while at the same time providing the proper reciprocal movement for the looper mechanism 44. Positioned laterally across the main crankshaft 91 from left to right on FIG. 6 are, first, the wishbone cam 99, then the needle offset journal assembly 100, then the punch offset journal assembly 101, and then the yoke cam 102. These elements are generally adjacent one another and each operates to provide a reciprocating vertical movement to respectively a wishbone cam follower 103, a needle connecting rod 104, a punch connecting rod 105, and a yoke cam follower 106. Extending upwardly from the wishbone cam follower 103 and generally within the shielding tube 107 is the wishbone push rod 108. Positioned within the sewing head case 25 just above the cam foilower 103 is the wishbone return spring 109 which operates to complete the reciprocating motion cycle with the wishbone cam 99. Attached to the needle connecting rod 104 at its upper end is the reciprocating needle piston assembly 110. The connecting rod 104 is, of course, pivotally connected to the needle pis- -ton assembly .110 such that the reciprocating movement of the connecting rod is transmitted to the vertically moving needle piston assembly 1 10. In a like manner the punch connecting rod at its upper end is pivotally connected to punch piston assembly designated as 111 through which the hole punching mechanism 42 secures its up and down vertical motion. Similarly communicating with the yoke cam follower 106 is a yoke push rod 1 12 which is contained within a similar shield member 113 and in a like manner a yoke return spring 114 is mounted within the sewing head case 25 at a position just above the yoke cam follower 106 in order to provide the downward movement of the yoke push rod 112. Of course, at the uppermost position of the stitching needle mechanism 43 is the actual vertically extending hooked needle 115 which is securely bottomed in an upwardly extending shank member 1 16 which is in turn fixed to the needle piston assembly 110. The vertical travel of the point of the hooked needle 115 is such that at bottom dead center the needle point will be slightly below the lowermost point that is reached by the looper mechanism 44. The vertical maximum or top dead center is a position where the needle hook is vertically above the uppermost face of the traveling core veneer such that the needle hook and thread thrower 3 are in operative communication. This will be more fully understood by referring to the operation of the invention. In a very similar manner, the hole punching mechanism 42 has an individual vertically extending punch 117 which is securely bottomed in an upwardly extending punch shank member 118 which in turn is operated by the vertical reciprocating motion of the punch piston assembly 111. The vertical movement of the punch 117 is very similar to that of the hooked needle 1 running from a bottom dead center position to a top dead center position which extends through the traveling core veneer such that a clean complete hole is punched in the veneer. The upward movement of the punch 117, as it passes through the core veneer and makes thehole, should take place just below and between the point of contact on the traveling veneer where the Wheels 48 and 49 are positioned. in this manner, a downwardly extending vertical force will be exerted by the rotating wheels 48, 49 as the punch 117 penetratesthe traveling veneer.

The looper mechanism 44 is actuated by the reciprocating vertical motions of the wishbone push rod 108 and yoke push rod 112. At the upper portion of the sewing head case there is a vertical motion translating section for the looper mechanism generally depicted as 119. It is the purpose of the translating device 119 to cause the pair of looper needles 122 to reciprocate in a highly structured motion just beneath the traveling core veneer in cooperation with the reciprocating hooked needle 115. The looper mechanism 44 is basically an element which is designed to pick a thread loop from the hooked needle 115 after it has pulled the loop through the formed hole, then carry it forward to the next stitching hole where the following downward motion of the hooked needle 1 15 with a new loop can pass through the threaded loop which is on the looper mechanism at which point the looper mechanism withdraws leaving its loop as part of the chain stitch. This action will be more fully described in the operation of the invention. Comprising the working part of the looper mechanism 44 are the pivoting yoke member 120, the vertically reciprocating wishbone member 121, and the pair of opposed reciprocating looper needles 122. The yoke 120 and wishbone 121 extend upwardly from the translating device 119 and are in operative communication with each other in order to impart the desired structured motion to the looper needles 122.

In order to translate the vertical reciprocating motion of the yoke push rod 112 to an axial pivoting motion, a lever arm 123 is attached on one end to a rotatable hollow shaft 124 (see FIG. 9). Of course, the upper end of yoke push rod 112 is pivotally connected to one end of the lever arm 123 and causes the lever arm 123, which is securely attached to the hollow shaft 124, to rotate about the laterally extending axis through the hollow shaft. Laterally spaced from the lever arm 123 is the pivotally mounted yoke 120. Suitable securing means indicated at 125 clamp the yoke 120 to the rotatable hollow shaft 124 in a fixed position where it will be allowed to pivot through a predetermined arc.

At the opposite end of the hollow shaft 124 is the translating device for laterally displacing the vertical motion of the wishbone push rod 108 to the vertically reciprocating wishbone 121. This translating device is comprised of a pivotally mounted generally axially extending lever arm 126 to which is attached the upper end of the wishbone push rod 10% at the connection point 127. The axial upstream end of the lever arm 126 is pivotally mounted within the upper portion of the sewing head case 25 through a pinned connection point 128 while the other end of the lever arm 126 has a laterally extending connector shaft 129 extending between it and the bottom of the vertically reciprocating wishbone 121. The wishbone 121 is pivotally attached to the connector shaft 129 and an aperture 130 is provided in the hollow shaft 124 such that the wishbone 121 can extend upwardly through the wall of shaft 124. As the wishbone 121 extends upwardly it, as the name implies, forms two upwardly extending wishbone legs, each indicated as 131.

At the upper portions of both the yoke 120 and wishbone legs 131, a plurality of connection points are provided in order to mount the pair of looper needles 122. In a manner similar to the formation of the wishbone legs 131, the yoke 120 is structured so as to have a pair of opposing pinned connection points both designated as 132. Likewise, at the uppermost portions of the wishbone legs 131, a similar pair of pinned pivotal connection points 133 is provided. It is, of course, the pair of looper needles 122 which has mounting holes therein and which is pivotally mounted by the use of the connection points 132 and 133. The looper needles 122 are comprised of two sections, one being the lever arm section 134 and the other being the upstream extending curvilinear portion 135. The outward ends of the looper needles 122 are mounted at the pinned connection points 132 while the other end of the lever arm section 134 is mounted at the connection points 133. The curved portion 135 then extends generally axially upstream and laterally inward. The laterally inward ends of the looper needles 122 will then reciprocate in an opening and closing motion in plan and a reciprocating curvilinear motion in elevation. This action will be more fully understood by referring to FIGS. 12 through 14 and to a description of the operation.

Turning now to a detailed description of the reciprocating thread thrower 3 and the thread tensioning apparatus 55 reference will be made primarily to FIG. 1 1.

The primary function of the reciprocating thread thrower 3 is to throw a loop of thread onto the hooked needle at the proper time after the needle has penetrated the hole in the traveling core veneer. As will be appreciated, after the loop of thread is on the hooked needle 115 the needle will withdraw back through the punched hole where the looper mechanism 44 will carry out its function of completing the chain stitch. The primary components of the reciprocating thread thrower 3 are the downwardly extending thread thrower arm 137 and the thread thrower motion translating device generally indicated at 138. It is through the motion translating device 13% that the rotational motion of the thread thrower drive shaft 87 is converted to a generally circular motion in a lateral plane at the stitching station 1 which will cause the thread to move about a structured circle with the aforementioned purpose being to position a thread loop on the hooked needle 115.

It should be apparent to one skilled in the art that the structure to translate the rotational motion on shaft 87 to the circular motion at the bottom of the thread thrower arm 137 can be comprised of an offset bearing housing 139 which is eccentrically mounted to the rotating drive shaft 87 so as to reciprocate the bearing housing 139 in both the vertical and axially directions. Then extending downwardly from the bearing housing 139, a two-legged forked member 140 is adapted to provide pivotal mountings 141 to a laterally extending thrower pivoting bar 142 which extends between the pivotal mountings 141 and a similar pivotal mounting 143 on the stationary supporting member 5. Then, laterally spaced from an axial line through the pivotal mountings 141 and extending downwardly therefrom is the thread thrower arm 137. At the very bottom of the thread thrower arm 137 is the thread thrower eye 144 through which the sewing thread is trained prior to commencing the stitching operation. It will be appreciated that the axial and vertical motions imparted to the pivoting bar 142 will be translated into the aforementioned circular motion at the thread thrower eye 144 due to the lateral offset of the thread thrower arm 137 on the pivoting bar 142. Of course, other suitable motion translating devices can be utilized to create the generally circular motion of the thread thrower eye in order to accomplish the intended purpose.

The thread tensioning apparatus 55, although not absolutely necessary for the operation of the instant invention, is desirable in that it sets the ideal amount of tension on the continuously flowing thread in order to make a secure tight chain stitch. In FIG. 11 a source of thread (not shown) is positioned above the reciprocating thread thrower 3 and its supporting member 5 in order to flow downwardly through the tensioning apparatus 55 and the thread thrower eye 144. First, the thread passes through a guide eye 145 which is positioned outwardly from the supporting member 5 through the guide arm 146.From the guide eye 145, the thread is directed to a first, spring operated, constant tension holding device 147. The thread is trained through a pair of cooperating wheels which always has the same amount of compression exerted between them and is that provided by the spring. The first ten sion device 147 is constructed so as to provide a constant thread tension to the second variable tension holding device 149.

During the chain stitching cycle, the moving parts which act on the thread will cause a varying amount of pull or tension on the thread and it is desirable although not absolutely necessary to provide a varying tension holding device in order to compensate for the variable slack which is produced. The variable tensioning device 149 merely utilizes the rotating motion of the drive shaft 87 and, through a spring actuated pair of wheels 150 which are similar to the wheels 148 and tension holding device 147, translates the rotating motion to a reciprocating axial motion which operates to vary the tension on the thread. This is accomplished by mounting an eccentric bearing 151 on the drive shaft 87 which has an outwardly extending reciprocating arm 152 thereon which is attached to a downwardly extending pivoting lever arm 153. At the upper and lower ends of the lever arm 153 a pair of pivotal connections 154 and 155 respectively hold the lever arm 153 in a generally vertical relationship with the sewing station 1. An aperture 156 through the lever arm 153 accepts a through bolt of the variable tension device 149 in such a manner that the pivoting lever arm 153 is allowed to reciprocate axially about the lower pivotal connection that the thrower arm 137 will never misplace a loop of 1 thread in relation to the hooked needle 115 and it also enhances the formation of good tight chain stitches.

Before proceeding to a description of the operation, one equivalent structure will be described which will provide the same desired function as that provided by the oscillating mechanism 36. It will be apparent to those skilled in the art that other suitable structures -would produce generally the same axial oscillating movement for the sewing head 2. For example, a cam and push rod arrangement could be substituted for the eccentrically operated connecting arm arrangement. Likewise, with the proper structuring, a single eccen tric journal and connecting rod arrangement could be designed which would approximate the desired motion for the sewing head. While these are reasonable alternate embodiments, it has been found that with the masses, inertias and speeds involved, the embodiment as depicted in the present drawing is the most desirable. The embodiment described above will yield a straight axial motion for the sewing head 2, that is zero acceleration in the downstream axial reciprocation movement, for more than a half-cycle while the punch and needle are engaged with the axially traveling veneer.

Operation of the Invention First to be described in terms of operation will be the chain stitch formation as the core veneer travels through the stitching station 1. After an understanding of the chain stitch formation is acquired, a description of critical adjustments will be given in order to establish proper timing of all moving elements.

In FIGS. 12 through 14 the chain stitch formation is graphically depicted. Referring first to FIG. 12, the directional arrow indicates the veneer travel direction through the stitching station 1. A plurality of previously formed chain stitches are as shown just to the right of the chain stitch being formed. In the sequence depicted in FIG. 12, the core veneer will be traveling forward at approximately 60 lineal feet per minute as will the hooked needle when it is physically through the appropriate hole in the veneer. The prior thread loop has been picked off the hook by the looper needles 122 prior to the upward movement of the hooked needle through the veneer. In this picking off motion by the looper needles 122 they will be traveling axially upstream as will the hooked needle. The looper needles 122 and the picked off thread loop will be further upstream than is the hooked needle 115. As the hooked needle 115 enters the appropriate hole in the traveling veneer, it has reversed its axial direction and is now traveling in a downstream direction in order to follow the path of the hole. When the hooked needle 1 15 is in its upper position, the thread thrower arm 137 loops the thread around the hook while at approximately the same time the hooked needle will begin its downward motion while continuing to travel axially downstream. As the hooked needle 1 15 withdraws from the traveling veneer with its new thread loop, the looper needles 122 are in a position to present the previously picked off loop of thread. In FIG. 13 the downwardly moving hooked needle with its thread loop has just penetrated the previously picked off thread loop which has been held by the looper needles 122. At this point, the looper needles 122 withdraw their holding function from the previously picked off thread loop and allow it to form the chain stitch with the new incoming thread loop on the hooked needle. At this point both the hooked needle 11S and looper needles 122 are ready to being their axial travel in the upstream direction. In FIG. 14 the hooked needle 115 with the new thread loop reaches bottom dead center and begins its upward motion toward the next appearing hole in the traveling core veneer. At this same instant, the looper needles 122 form a sharp point through the action of the wishbone legs 131 and it begins to travel faster axially upstream than does the hooked needle and as it passes the top of the needle, it pierces the thread loop and picks it off the upwardly moving needle. The clean hooked needle then continues upwardly and enters the next oncoming hole in order to receive another thread loop from the thread thrower arm 137. Just prior to the entrance of the hooked needle back into the veneer, the oscillator mechanism 36 reverses the axial direction of the hooked needle 115. The looper needles 122 will maintain the proper relative position of the picked off thread loop in order to allow the needle to secure a new loop and pass back through the hole in order to make another chain stitch. This cycle continually repeats and a thread line of chain stitches is formed in the axial direction as the core veneer continuously travels through the stitching station 1. The hole punching mechanism 42 operates in terms of vertical and axial motion very similar to that of the hooked needle 115, in that a hole is punched and the punch 117 then travels axially downstream with the core veneer as it is withdrawn through its downward movement. It then is actuated axially by the oscillator mechanism 36 to a position upstream where it will punch the next hole.

In order to complete the full and accurate description of the present invention, a timing procedure must be explained in order to allow all of the moving parts to be properly coordinated during operation. First, when the sewing head 2 is laterally positioned on the laterally extending shaft 6, it must not interfere with the stitching conveyors 12, 13 or the frame means 10, 51. The reciprocating thread thrower 3 must then be positioned relative to the sewing head 2. The intent here is to position the thread thrower eye 144 such that it will make the proper circular throw around the upwardly extended hooked needle. Prior to mounting the sewing head case 25 within the stationary base member 4, the stitching needle mechanism 43 and hole punching mechanism 42 are positioned near bottom dead center. In this position, the spur gear 90 is meshed with the crankshaft spur gear 92 and the case 25 is clamped'into position through the holding plates 32, 33 and the handles 35.

In order to time the oscillating mechanism 36, the oscillator drive shaft 85 must be timed with respect to the second cooperating drive shaft 93. This is done by meshing the cooperating upper and lower spur gears 94 and 95 respectively with the pair of eccentrics 96, 97 positioned approximately at bottom dead center. When finally connecting the stitching conveyors, this position must correspond to the position where the main crankshaft 91 in the sewing head case 25 will be in the top dead center position.

In order to time the reciprocating thread thrower 35 to the position of the sewing head crankshaft 91 and the oscillator shafts and Q3, the eccentrically mounted bearing housing 139 should be secured to the thread thrower drive shaft 87 in a position which is approximately 4l before top dead center of the eccentric. After this position is established, all of the driving chains can be interconnected and the proper timing will be in affect.

Prior to carrying out the several procedures just described, the looper mechanism 44 must be adjusted to provide the proper movement for the looper needles 122. A new straight needle should be installed within the shank member 116 with the hook facing the same direction as the looper needles 122 and with the shank 116 fully bottomed in the needle piston assembly 1 10. With the main crankshaft 9K in a position approximately 90 before bottom dead center the pivotally mounted yoke is positioned on its rotatable hollow shaft 124 so that the tips of the looper needles 122 are in front of the hooked needle vertical centerline. The crankshaft 91 is then rotated in a counter clockwise direction facing the drive end of the crankshaft, to a position approximately 20 after bottom dead center. With the crankshaft 91 in this position, the tips of the looper needles 122 are adjusted by changing the vertical height of the connector shaft 129 so that the tips are level with the horizontal centerline of the pinned pivotal connection points 132 in the yoke 12%). At this position, the needle tips must be touching each other and aligned so that together they form one sharp point for piercing the thread loop on the hooked needle 115.

The proper lateral position of the single sharp point must then be established so that the point passes precisely over the vertical centerline of the hooked needle 115. This is adjusted by laterally sliding the yoke 120 on its rotatable shaft 124 and then clamping it in its finally fixed position. After the above noted procedure has been carried out, the sewing head case 25 is ready to be installed within the base member 4 and to be timed with the thread thrower 3 and oscillating mechanism 36 as described above.

Thus, there has been described a core unitizing sewing machine which will stitch together individual pieces of core veneer in a fast continuous manner while establishing tight joints through a strong chain stitch. Since the punching action to form the holes in the solid material is separate from the needle action, little frictional heat is created when the needle penetrates the veneer. The oscillating mechanism provides a highly structured axial motion for the sewing head and provides zero acceleration when the hooked needle is in the veneer so that needle breakage is virtually eliminated and, in fact, the needle need not contact the core veneer at all while at the same time it moves at the same continuous speed as does the traveling veneer.

While a detailed example of the principal embodiment has been described, it is understood that many changes and modifications may be made in the above described core unitizing machine without departing from the spirit of the invention. All such modifications are intendedto be included within the scope of the appended claims.

What is claimed is:

ll. A sewing machine for forming chain stitches comprised of a suitable thread in a continuously traveling workpiece, comprising workpieces axially through said sewing machine,

an axially reciprocating sewing head positioned generally below the horizontal plane along which the workpiece travels, comprising in operative communication:

a. a vertically reciprocating hole forming mechaposition a loop of thread about said needle mechanism when the needle mechanism is up through and in engagement with said workpiece, and

means to stabilize said workpiece in a substantially fixed vertical'position as each of said apertures is formed in order to provide a clean well formed aperture.

nism which is adapted to form an aperture within said workpiece and travel with it in an engaged relationship for a portion of the sewing head axial reciprocation movement,

b. a vertically reciprocating needle mechanism positioned downstream from said hole forming mechanism and adapted to penetrate one of said previously formed apertures, traveling with said workpiece in an engaged relationship for a portion of the sewing head axial reciprocation movement,

c. a reciprocating looper mechanism adapted to pick a thread loop from said needle mechanism when said needle mechanism pulls said thread loop downwardly through the aperture in said 2. The sewing machine as in claim 1 in which said means to axially reciprocate said sewing head comprise a pair of spaced eocentrically mounted axially reciprocating arm members with each being connected to opposite ends of a joining arm such that the motion imparted to a connection point on said joining arm represents the sum of the axial motions produced by said arm members and further comprising means to pivotally connect said connection point to said sewing head.

3. The sewing machine as in claim 1 further including a thread tensioning apparatus which is positioned so as to act on the thread prior to its being positioned on said needle mechanism such that tension will always be apworkpiece and to hold said loop so that the next plied to Said thread the sfitches are Succeeding loop can be brought through the held 4. The sewing machine as in claim 1 further including preceding 1 whereupon said preceding held a generally horizontal foot member positioned above loop i released f Said looper mechanism but laterally offset from the position at which said neethereby forming said chain stitches, and dle mechmiSm-emem said workpieced. means to reciprocate said sewing head axially in The g machine aS'in C a 1 i ich Said synchronous relationship with said hole forming rkpiece S ng eans is comprised of at least mechanism, said needle mechanism, and s id one punch wheel positioned above but laterally offset looper mechanism, from the position at which said hole punching mechaa reciprocating thread thrower positioned generally nism forms said apertures.

above said needle mechanism and having means to 

1. A sewing machine for forming chain stitches comprised of a suitable thread in a continuously traveling workpiece, comprising means to continuously feed generally horizontal workpieces axially through said sewing machine, an axially reciprocating sewing head positioned generally below the horizontal plane along which the workpiece travels, comprising in operative communication: a. a vertically reciprocating hole forming mechanism which is adapted to form an aperture within said workpiece and travel with it in an engaged relationship for a portion of the sewing head axial reciprocation movement, b. a vertically reciprocating needle mechanism positioned downstream from said hole forming mechanism and adapted to penetrate one of said previously formed apertures, traveling with said workpiece in an engaged relationship for a portion of the sewing head axial reciprocation movement, c. a reciprocating looper mechanism adapted to pick a thread loop from said needle mechanism when said needle mechanism pulls said thread loop downwardly through the aperture in said workpiece and to hold said loop so that the next succeeding loop can be brought through the held preceding loop whereupon said preceding held loop is released from said looper mechanism thereby forming said chain stitches, and d. means to reciprocate said sewing head axially in synchronous relationship with said hole forming mechanism, said needle mechanism, and said looper mechanism, a reciprocating thread thrower positioned generally above said needle mechanism and having means to position a loop of thread about said needle mechanism when the needle mechanism is up through and in engagement with said workpiece, and means to stabilize said workpiece in a substantially fixed vertical position as each of said apertures is formed in order to provide a clean well formed aperture.
 2. The sewing machine as in claim 1 in which said means to axially reciprocate said sewing head comprise a pair of spaced eccentrically mounted axially reciprocating arm members with each being connected to opposite ends of a joining arm such that the motion imparted to a connection point on said joining arm represents the sum of the axial motions produced by said arm members and further comprising means to pivotally connect said connection point to said sewing head.
 3. The sewing machine as in claim 1 further including a thread tensioning apparatus which is positioned so as to act on the thread prior to its being positioned on said needle mechanism such that tension will always be applied to said thread as the chain stitches are formed.
 4. The sewing machine as in claim 1 further including a generally horizontal foot member positioned above but laterally offset from the position at which said needle mechanism enters said workpiece.
 5. The sewing machine as in claim 1 in which said workpiece stabilizing means is comprised of at least one punch wheel positioned above but laterally offset from the position at which said hole punching mechanism forms said apertures. 